Événements
Séminaire IQ - Wolfgang Belzig
Date : 16 avril 2024 11:00
Type : Institut Quantique
Lieu :
Lieu/Location : Auditorium de l'IQ
Langue/Language : English
Wolfgang Belzig
Universität Konstanz
Invité de Bertrand Reulet
Titre/Title
Topological states in multi-terminal superconducting structures
Résumé/Abstract
Topology is ultimately unveils the roots of the perfect quantization observed in complex systems. The 2D quantum Hall effect is the celebrated archetype. In recent years, various classes of systems were proposed to realize analogous topological states of matter. One of them are multiterminal Josephson junctions where topological Andreev bound states are constructed in the synthetic space of superconducting phases. Crucially, the topology in these systems results in a quantized transconductance between two of its terminals comparable to the quantum Hall effect.
In this talk, I report our work on superconducting quantum dot structures with four or more superconducting terminals [1] that display a nontrivial topology and possess Weyl singularities in the space of synthetic dimensions. I will show that the topology can be accessed by Berry spectroscopy which reveal the local Berry curvature. Furthermore I touch on a the intriguing possibility to realize higher-dimensional topology and non-Abelian Berry phase [2] in superconducting systems. I also show that Coulomb repulsion between electrons usually present in quantum dot setups maintain non-trivial phases [3] and discuss how the topological phases can be optimized in parameter space. Finally, I report on the first experimental steps [4] towards realizing topological non-trivial Andreev states.
[1] R. L. Klees, G. Rastelli, J. C. Cuevas, and W. Belzig
Microwave spectroscopy reveals the quantum geometric tensor of topological Josephson matter
Phys. Rev. Lett. 124, 197002 (2020).
[2] H. Weisbrich, R.L. Klees, G. Rastelli and W. Belzig
Second Chern Number and Non-Abelian Berry Phase in Superconducting Systems
PRX Quantum 2, 010310 (2021).
[3] L. Teshler, H. Weisbrich, J. Sturm, R. L. Klees, G. Rastelli, W. Belzig
SciPost Phys. 15, 214 (2023).
[4] M. Coraiola, D. Z. Haxell, D. Sabonis, H. Weisbrich, A. E. Svetogorov, M. Hinderling, S. C. ten Kate, E. Cheah, F. Krizek, R. Schott, W. Wegscheider, J. C. Cuevas, W. Belzig, and F. Nichele
Phase-engineering the Andreev band structure of a three-terminal Josephson junction
Nat. Commun. 14, 6784 (2023).
Langue/Language : English
Wolfgang Belzig
Universität Konstanz
Invité de Bertrand Reulet
Titre/Title
Topological states in multi-terminal superconducting structures
Résumé/Abstract
Topology is ultimately unveils the roots of the perfect quantization observed in complex systems. The 2D quantum Hall effect is the celebrated archetype. In recent years, various classes of systems were proposed to realize analogous topological states of matter. One of them are multiterminal Josephson junctions where topological Andreev bound states are constructed in the synthetic space of superconducting phases. Crucially, the topology in these systems results in a quantized transconductance between two of its terminals comparable to the quantum Hall effect.
In this talk, I report our work on superconducting quantum dot structures with four or more superconducting terminals [1] that display a nontrivial topology and possess Weyl singularities in the space of synthetic dimensions. I will show that the topology can be accessed by Berry spectroscopy which reveal the local Berry curvature. Furthermore I touch on a the intriguing possibility to realize higher-dimensional topology and non-Abelian Berry phase [2] in superconducting systems. I also show that Coulomb repulsion between electrons usually present in quantum dot setups maintain non-trivial phases [3] and discuss how the topological phases can be optimized in parameter space. Finally, I report on the first experimental steps [4] towards realizing topological non-trivial Andreev states.
[1] R. L. Klees, G. Rastelli, J. C. Cuevas, and W. Belzig
Microwave spectroscopy reveals the quantum geometric tensor of topological Josephson matter
Phys. Rev. Lett. 124, 197002 (2020).
[2] H. Weisbrich, R.L. Klees, G. Rastelli and W. Belzig
Second Chern Number and Non-Abelian Berry Phase in Superconducting Systems
PRX Quantum 2, 010310 (2021).
[3] L. Teshler, H. Weisbrich, J. Sturm, R. L. Klees, G. Rastelli, W. Belzig
SciPost Phys. 15, 214 (2023).
[4] M. Coraiola, D. Z. Haxell, D. Sabonis, H. Weisbrich, A. E. Svetogorov, M. Hinderling, S. C. ten Kate, E. Cheah, F. Krizek, R. Schott, W. Wegscheider, J. C. Cuevas, W. Belzig, and F. Nichele
Phase-engineering the Andreev band structure of a three-terminal Josephson junction
Nat. Commun. 14, 6784 (2023).